In general, doors are attached to household furniture such as a wardrobe, bookcase, etc. or a kitchen cabinet by spring hinges so as to be able to be easily opened and closed with weak force. When closed, the door bumps against a doorframe, so that there is a possibility of causing noise or accident.
Particularly, when carelessly abruptly closing the door, a child is injured in the finger, which is pinched between the doorframe and the door.
In order to overcome this problem, a door damper as illustrated in FIG. 9 has been developed.
This door damper is designed to use a check valve to rapidly close the door by increasing the cross section of a channel through which oil, in an oil chamber, passes when an impact is weak, and to absorb the impact by narrowing the channel cross section when the impact is strong.